Abstract: An ultrasonic tissue resector is slidably engaged with a working channel of a flexible neuroendoscope for resecting brain tumors, cysts, hematomas, and herniated spinal discs. The resector includes a piezoelectric transducer for generating ultrasonic energy. The ultrasonic energy is coupled to an ultrasonic probe having a rigid proximal segment for transmitting the energy therealong and a flexible distal segment which can bend to conform to the flexible neuroendoscope. An aspiration channel is provided, and the resector can be endoscopically positioned in the brain through the neuroendoscope and energized to ultrasonically break up tissue such as tumors, cysts, and hematomas and remove the tissue through the aspiration channel.